Light emitting devices such as light emitting diodes (LEDs) are used in electronic displays, such as liquid crystal displays in laptop computers or LED televisions. Conventional LED units are fabricated by mounting LEDs to a substrate, encapsulating the mounted LEDs and then optically coupling the encapsulated LEDs to an optical waveguide, such as a light guide plate in a back light unit of a liquid crystal display. Some of the problems that conventional LED units can suffer include general lack of color uniformity across the light guide plate.